Thermoset adhesive films

ABSTRACT

This invention is a film adhesive prepared from an adhesive composition comprising a polymer system, a film forming rubber compound, and curing agents for the polymeric system. The polymer system comprises a base polymer and electron donor and electron acceptor functionality.

FIELD OF THE INVENTION

[0001] This invention relates to film adhesives, and particularly filmadhesives for use in semiconductor packaging

BACKGROUND OF THE INVENTION

[0002] A common mode of electronics packaging involves affixingsemiconductor devices onto substrates by means of an adhesive tape.Epoxy compounds and resins currently are among the most commonly usedmaterials for current film based adhesive applications, such as dieattach, in which a semiconductor die is attached to a substrate. In atypical embodiment, a film-forming rubber polymer is blended with epoxyresins and a hardening agent. These compositions can then be cured uponapplication of heat, which results in the development of a thermosetnetwork. One drawback to epoxy adhesives is their ultimate latency.Typically, these materials must be stored at low temperature to avoidpremature advancement of the adhesive. Moreover, the speed of cure forthese compositions is relatively slow making the die-attach operationthe least efficient step in the total assembly manufacturing process forwirebonded integrated circuit packages. This creates a need for a filmadhesive that can be rapidly cured compared to the conventionalthermoset film adhesives, and particularly to films containing no epoxy.

SUMMARY OF THE INVENTION

[0003] This invention is a film adhesive prepared from an adhesivecomposition comprising a polymer system, a film forming rubber compound,and curing agents for the polymeric system. In a preferred embodimentthe polymer system contains no epoxy functionality. The polymer systemcomprises a base polymer and electron donor and electron acceptorfunctionality. The electron donor and electron acceptor functionalitycan be pendant from the base polymer, or can be interdispersed with thebase polymer as independent compounds. In some cases, the base polymercan function as a film-forming rubber compound. The film can be prepareddirectly as a monolayer from the adhesive composition, or from coatingthe adhesive composition onto both sides of a thermal resistant tapesubstrate.

DETAILED DESCRIPTION OF THE INVENTION

[0004] The polymer system for preparing the film adhesives will containa base polymer (hereinafter “polymer” or “base polymer”) and electrondonor and electron acceptor functionality. The system can be segregatedinto several classes: (1) an unsubstituted base polymer blended with anindependent electron donor compound and an independent electron acceptorcompound; (2) a base polymer substituted with pendant electron acceptorfunctionality, blended with an independent electron donor compound, andoptionally an independent electron acceptor compound; (3) a base polymersubstituted with pendant electron donor functionality, blended with anindependent electron acceptor compound and optionally an independentelectron donor compound; (4) a base polymer substituted with pendantelectron donor and electron acceptor functionality, or a combination ofa base polymer substituted with pendant electron donor functionality anda base polymer substituted with pendant electron acceptor functionality,optionally blended with an independent electron donor compound, or anindependent electron acceptor compound, or both.

[0005] Preferably, there will be a 1:1 molar ratio of electron donor toelectron acceptor; however, the molar ratio can range from0.01-1.0:1.0-0.01.

[0006] A suitable base polymer in the polymer system of the inventivefilm adhesive is prepared from acrylic and/or vinyl monomers usingstandard polymerization techniques. The acrylic monomers that may beused to form the base polymer include α,β-unsaturated mono anddicarboxylic acids having three to five carbon atoms and acrylate estermonomers (alkyl esters of acrylic and methacrylic acid in which thealkyl groups contain one to fourteen carbon atoms). Examples are methylacryate, methyl methacrylate, n-octyl acrylate, n-nonyl methacrylate,and their corresponding branched isomers, such as, 2-ethylhexylacrylate. The vinyl monomers that may be used to form the base polymerinclude vinyl esters, vinyl ethers, vinyl halides, vinylidene halides,and nitriles of ethylenically unsaturated hydrocarbons. Examples arevinyl acetate, acrylamide, 1-octyl acrylamide, acrylic acid, vinyl ethylether, vinyl chloride, vinylidene chloride, acrylonitrile, maleicanhydride, and styrene.

[0007] Another suitable base polymer in the polymer system of theinventive film adhesive is prepared from conjugated diene and/or vinylmonomers using standard polymerization techniques. The conjugated dienemonomers that may be used to form the polymer base includebutadiene-1,3, 2-chlorobutadiene-1,3, isoprene, piperylene andconjugated hexadienes. The vinyl monomers that may be used to form thebase polymer include styrene, α-methylstyrene, divinylbenzene, vinylchloride, vinyl acetate, vinylidene chloride, methyl methacrylate, ethylacrylate, vinylpyridine, acrylonitrile, methacrylonitrile, methacrylicacid, itaconic acid and acrylic acid.

[0008] Alternatively, the base polymer can be purchased commercially.Suitable commercially available polymers include acrylonitrile-butadienerubbers from Zeon Chemicals and styrene-acrylic copolymers from JohnsonPolymer.

[0009] In those systems in which the base polymer is substituted withelectron donor and/or electron acceptor functionality, the degree ofsubstitution can be varied to suit the specific requirements forcross-link density in the final applications. Suitable substitutionlevels range from 6 to 500, preferably from 10 to 200.

[0010] The base polymer, whether substituted or unsubstituted will havea molecular weight range of 2,000 to 1,000,000. The glass transitiontemperature (Tg) will vary depending on the specific base polymer. Forexample, the Tg for butadiene polymers ranges from −100° C. to 25° C.,and for modified acrylic polymers, from 15° C. to 50° C.

[0011] Suitable electron donor functionality includes vinyl ethergroups, vinyl silane groups, and carbon to carbon double bonds externalto an aromatic ring and conjugated with the unsaturation in the aromaticring. Suitable electron acceptor groups include maleimides, acrylates,fumarates and maleates.

[0012] Examples of suitable starting materials for reacting withcomplementary functionality on the base polymer in order to add theelectron donor or electron acceptor functionality pendant to the basepolymer include: for electron donor functionality, hydroxybutyl vinylether, cinnamyl alcohol, 1,4-cyclohexane-dimethanol monovinyl eether,3-isopropenyl-α,α-dimethylbenzyl isocyanate, isoeugenol, and thederivatives of the aforementioned compounds; for electron acceptorfunctionality, dioctyl maleate, dibutyl maleate, dioctyl fumarate,dibutyl fumarate, N-(6-hydroxyhexyl) maleimide, 6-maleimidocaproic acid,and 3-maleimidopropionic acid.

[0013] Independent electron donor compounds for blending with the basepolymer include compounds having at least two vinyl ether groups, orhaving at least two carbon to carbon double bonds external to aromaticrings and conjugated with the unsaturation in the aromatic ring.Suitable divinyl ether examples include compounds such asbis[4-(vinyloxy)butyl]terephthalate, bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)biscarbamate, bis[4-(vinyloxy) butyl]1,6-hexanediylbiscarbamate, 4-(vinyloxy)butyl stearate, andbis[4-(vinyloxy)butyl] (methylenedi-4,1-phenylene)biscarbamate (soldunder the trade name Vectomer from Morflex, Inc). Exemplary compoundshaving at least two carbon to carbon double bonds external to aromaticrings and conjugated with the unsaturation in the aromatic ring include:

[0014] the adduct of tricyclodecane-dimethanol and3-isopropenyl-α,α-dimethylbenzyl isocyanate (m-TMI) having the structure

[0015] the adduct of 2-hydroxyethyl disulfide and m-TMI having thestructure

[0016] the adduct of cyanurate/trifunctional isocyanate and cinnamylalcohol having the structure

[0017] the adduct of 1,3-propanediol and M-TMI having the structure

[0018] the adduct of 1,4-butanediol and M-TMI having the structure

[0019] and the adduct of cinnamyl alcohol and 1,6-diisocyanatohexanehaving the structure

[0020] These compounds can be prepared by standard synthetic methodsknown to those skilled in the art without undue experimentation.

[0021] Independent electron acceptor compounds for blending with thebase polymer include resins having at least two intramolecularmaleimide, acrylate, fumarate or maleate groups. Examples ofbismaleimides include: N,N′-ethylene-bis-maleimide,N,N′-butylene-bis-maleimide, N,N′-phenylene-bis-maleimide,N,N′-hexamethylene-bis-maleimide, N,N′-4,4′-diphenylmethane-bis-maleimide, N,N′-4,4′-diphenyl ether-bis-maleimide,N,N′-4,4′-diphenyl sulfone-bis-maleimide, N,N′-4,4′-dicyclohexylmethane-bis-maleimide, N,N′-xylylene-bis-maleimide, N,N′-diphenylcyclohexane-bis-maleimide and the like.

[0022] Suitable film forming resins or compounds include acrylicpolymers (sold under the trade name TEISAN RESIN from Nagase ChemteXCorporation) and acrylonitrile-butadiene elastomers (sold under thetrade name NIPOL from Zeon Chemicals). These materials, in general, willbe present in the adhesive composition from which the film will beprepared, in an amount ranging from 10% to 70%, preferably 15% to 50%,by weight of the adhesive formulation. Other levels may be suitabledepending on the end use application, and optimal levels can bedetermined without undue experimentation on the part of the formulator.

[0023] Suitable curing agents for the polymer system are thermalinitiators and photoinitiators, present in an amount of 0.1% to 10%,preferably 0.1% to 5.0%, by weight of the polymer system. Preferredthermal initiators include peroxides, such as butyl peroctoates anddicumyl peroxide, and azo compounds, such as2,2′-azobis(2-methyl-propanenitrile) and2,2′-azobis(2-methyl-butanenitrile). A preferred series ofphotoinitiators is one sold under the trademark Irgacure by CibaSpecialty Chemicals. In some formulations, both thermal initiation andphotoinitiation may be desirable; for example, the curing process can bestarted by irradiation, and in a later processing step curing can becompleted by the application of heat to accomplish the thermal cure. Ingeneral, these compositions will cure within a temperature range of 70°C. to 250° C., and curing will be effected at a temperature within therange of ten seconds to three hours. The time and temperature curingprofile of each formulation will vary with the specific electron donorcompound and the other components of the formulation, but the parametersof a curing profile can be determined by a practitioner skilled in theart without undue experimentation.

[0024] In some cases, it may be an advantage to add an epoxy compound orresin to the adhesive composition. Suitable epoxy compounds or resinsinclude bifunctional and polyfunctional epoxy resins such as bisphenolA-type epoxy, cresol novolak epoxy, or phenol novolak epoxy. Anothersuitable epoxy resin is a multifunctional epoxy resin from Dainippon Inkand Chemicals, Inc. (sold under the product number HP-7200). When addedto the formulation, the epoxy will be present in an amount up to 80% byweight.

[0025] If an epoxy compound is added, the formulation will need tocontain a curing or hardening agent for the epoxy. Suitable curingagents include amines, polyamides, acid anhydrides, polysulfides,trifluoroboron, and bisphenol A, bisphenol F and bisphenol S, which arecompounds having at least two phenolic hydroxyl groups in one molecule.A curing accelerator may also be used in combination with the curingagent. Suitable curing accelerators include imidazoles, such as2-methylimidazole, 2-ethyl-4-methylimidazole,4-methyl-2-phenylimidazole, and 1-cyanoethyl-2-phenylimidazoliumtrimellitate. The curing agents and accelerators are used in standardamounts known to those skilled in the art.

[0026] Other materials, such as adhesion promoters (epoxides, silanes),dyes, pigments, and rheology modifiers, may be added as desired formodification of final properties. Such materials and the amounts neededare within the expertise of those skilled in the art.

[0027] Filler particles that enhance the mechanical, electricalconductivity, or thermal conductivity may also be added. Suitableconductive fillers are carbon black, graphite, gold, silver, copper,platinum, palladium, nickel, aluminum, silicon carbide, boron nitride,diamond, and alumina. Suitable nonconductive fillers are particles ofvermiculite, mica, wollastonite, calcium carbonate, titania, sand,glass, fused silica, fumed silica, barium sulfate, and halogenatedethylene polymers, such as tetrafluoroethylene, trifluoroethylene,vinylidene fluoride, vinyl fluoride, vinylidene chloride, and vinylchloride. When present, fillers will be in amounts of 0.1% to 90%,preferably from 5% to 90%, by weight of the formulation.

POLYMER SYNTHETIC EXAMPLES Example 1

[0028] This example discloses a butadiene/acrylonitrile base polymercontaining pendant acrylate (electron acceptor) functionality.

[0029] where x=50, y=5, n=310, p=678, and q=59, based on GPC and NMRanalysis (one skilled in the art will recognize that these values mayvary slightly due to the polymeric character of the material).

[0030] Carboxylated butadiene/acrylonitrile polymer (50.6 g) (Nipol 1072from Zeon Chemicals) was solvated in 4-methyl-2-pentanone (MIBK, 250 mL)in a 500 mL four-necked flask equipped with a mechanical stirrer,condenser and drying tube. Glycidyl methacrylate (9.78 g) andtetrabutylphosphonium acetate solution (0.58 g) (TBPAAC, catalyst, 70%by weight of tetrabutylphosphonium acid acetate in methanol from MortonInternational, Inc.) were added to the mixture with stirring. Themixture was heated to 110° C. and held at that temperature forapproximately twelve hours. The final product has a viscosity of 4870mPa.s at ambient temperature and according to titration results of theresidual carboxylic acid of the modified Nipol rubber, the carboxylconversion is about 90%. According to GPC analysis, the weight averagemolecular weight and the number average molecular weight of the modifiedNipol polymer are 430,500 g/mol and 60,900 g/mol, respectively.

Example 2

[0031] This example discloses a butadiene/acrylonitrile base polymerwith pendant styrenic (electron donor) functionality,

[0032] where x=56, y=16, n=401, p=877, and q=76 based on GPC and NMRanalysis (one skilled in the art will recognize that these values mayvary slightly due to the polymeric character of the material).

[0033] Carboxylated butadiene/acrylonitrile polymer (38.0 g) (Nipol 1072from Zeon Chemicals) was solvated in 4-methyl-2-pentanone (MIBK, 255 mL)in a 500 mL four-necked flask equipped with a mechanical stirrer,condenser and drying tube. Isoeugenol glycidyl ether (11.43 g) andtetrabutylphosphonium acetate solution (0.62 g) (TBPAAC, catalyst, 70%by wetight of tetrabutylphosphonium acid acetate in methanol from MortonInternational, Inc.) were added into the mixture with stirring. Themixture was heated to 110° C. and held at that temperature forapproximately fourteen hours. According to titration results of theresidual carboxylic acid of the modified Nipol rubber, the carboxylconversion is about 87%. The product was purified by precipitation inmethanol three times. According to GPC analysis, the weight averagemolecular weight and the number average molecular weight of the modifiedNipol polymer are 554,400 g/mol and 89,100 g/mol, respectively.

Example 3

[0034] This example discloses a butadiene/acrylonitrile base polymerwith pendant styrenic (electron donor) functionality,

[0035] where x 49, y=7, n=310, p=739, and q=59 based on GPC and NMRanalysis (one skilled in the art will recognize that these values mayvary slightly due to the polymeric character of the material).

[0036] Carboxylated butadiene/acrylonitrile polymer (53.8 g) (Nipol 1072from Zeon Chemicals) was solvated in 4-methyl-2-pentanone (MIBK, 360 mL)in a 1 L four-necked flask equipped with a mechanical stirrer, condenserand drying tube. Glycidyl N-(3-isopropenyl-α,α-dimethylbenzyl) carbamate(14.8 g) and tetrabutylphosphonium acetate solution (0.54 g) (TBPAAC,catalyst) were added into the mixture with stirring. The mixture washeated to 105° C. and held at that temperature for approximately fifteenhours. The final product has a viscosity of 2000 mPa.s at ambienttemperature and according to titration results, the carboxyl conversionis about 88%. According to GPC analysis, the weight average molecularweight and the number average molecular weight of the modified Nipolpolymer are 666,000 g/mol and 75,600 g/mol, respectively.

Example 4

[0037] This example discloses a butadiene/acrylonitrile base polymerwith pendant cinnamyl (electron donor) functionality,

[0038] A solution of carboxylated butadiene/acrylonitrile polymer (onemolar equivalent based on the carboxylic acid) in toluene is reactedwith excess thionyl chloride at 50° C. for approximately fourteen hours.The excess thionyl chloride and the solvent are removed under reducedpressure to afford the butadiene/acrylonitrile polymer with pendant acidchloride.

[0039] One molar equivalent of cinnamyl alcohol and one molar equivalentof triethylamine are mixed in dry toluene at 0° C., to which is addedthe butadiene/acrylonitrile polymer with pendant acid chloride dissolvedin dry toluene (one molar equivalent based on the acid chloride). Themixture is allowed to react overnight. The product is purified byprecipitation in methanol three times.

Example 5

[0040] This example discloses a butadiene/acrylonitrile base polymerwith pendant cinnamyl (electron donor) functionality,

[0041] One molar equivalent of cinnamyl amine and one molar equivalentof triethylamine are mixed in dry toluene at 0° C., to which is addedthe butadiene/acrylonitrile polymer with pendant acid chloride dissolvedin dry toluene (one molar equivalent based on the acid chloride). Themixture is allowed to react overnight. The product is purified byprecipitation in methanol three times.

Example 6

[0042] This example discloses a butadiene/acrylonitrile base polymerwith pendant styrenic (electron donor) functionality,

[0043] One molar equivalent of isoeugenol and one molar equivalent oftriethylamine are mixed in dry toluene at 0° C., to which is added thebutadiene/acrylonitrile polymer with pendant acid chloride dissolved indry toluene (one molar equivalent based on the acid chloride). Themixture is allowed to react overnight. The product is purified byprecipitation in methanol three times.

Example 7

[0044] This example discloses a butadiene/acrylonitrile base polymerwith pendant styrenic (electron donor) functionality,

[0045] One molar equivalent of 4-vinyl benzyl amine and one molarequivalent of triethylamine are mixed in dry toluene at 0° C., to whichis added the butadiene/acrylonitrile polymer with pendant acid chloridedissolved in dry toluene (one molar equivalent based on the acidchloride). The mixture is allowed to react overnight. The product ispurified by precipitation in methanol three times.

Example 8

[0046] This example discloses a butadiene/acrylonitrile base polymerwith pendant vinyl ether (electron donor) functionality,

[0047] One molar equivalent of 4-hydroxybutyl vinyl ether and one molarequivalent of triethylamine are mixed in dry toluene at 0° C., to whichis added the butadiene/acrylonitrile polymer with pendant acid chloridedissolved in dry toluene (one molar equivalent based on the acidchloride). The mixture is allowed to react overnight. The product ispurified by precipitation in methanol three times.

Example 9

[0048] This example discloses a butadiene/acrylonitrile base polymerwith pendant vinyl ether (electron donor) functionality,

[0049] One molar equivalent of 2-aminoethyl vinyl ether and one molarequivalent of triethylamine are mixed in dry toluene at 0° C., to whichis added the butadiene/acrylonitrile polymer with pendant acid chloridedissolved in dry toluene (one molar equivalent based on the acidchloride). The mixture is allowed to react overnight. The product ispurified by precipitation in methanol three times.

Example 10

[0050] This example discloses a hydroxylated styrene/butadiene basepolymer with pendant styrenic (electron donor) functionality,

[0051] One molar equivalent (based on hydroxyl function) of hydroxylatedstyrene/butadiene polymer is solvated in dry toluene at 90° C. undernitrogen, followed by the addition of one molar equivalent of3-isopropenyl-α,α-dimethylbenzyl isocyanate (m-TMI) together with 0.07%of dibutyltin dilaurate (catalyst) based on the total amount ofreactants. The resulting mixture is heated for an additional twenty-fourhours under nitrogen. After removal of the solvent under reducedpressure, the product is obtained in almost quantitative yield.

Example 11

[0052] This example discloses a hydroxylated styrene/butadiene basepolymer having pendant styrenic (electron donor) functionality,

[0053] One molar equivalent of butadiene/styrene polymer based on the1,2-vinyl bonds is solvated in dry toluene under nitrogen and 0.3 molarequivalent of 2-mercaptoethanol is added into the mixture, followed byheating to 75° C. A solution of azodiisobutyronitrile (AIBN) in tolueneis then added to the mixture. The mixture is stirred at 75° C. for 7hours. The product is purified by precipitation in methanol three times.

[0054] One molar equivalent (based on hydroxyl function) of hydroxylatedstyrene/butadiene polymer prepared as above is solvated in dry tolueneat 90° C. under nitrogen, followed by the addition of one molarequivalent of 3-isopropenyl-α,α-dimethylbenzyl isocyanate (m-TMI)together with 0.07% of dibutyltin dilaurate (catalyst) based on thetotal amount of reactants. The resulting mixture is heated for anadditional twenty-four hours under nitrogen. After removal of thesolvent under reduced pressure, the product is obtained in almostquantitative yield.

Example 12

[0055] This example discloses a hydroxylated styrene/butadiene basepolymer having pendant maleimide (electron acceptor) functionality,

[0056] One molar equivalent (based on hydroxyl function) of hydroxylatedstyrene/butadiene polymer prepared as in Example 11 is solvated in drytoluene at 90° C. under nitrogen, followed by the addition of one molarequivalent of 6-maleimidocaproic acid in toluene. Catalytic amount ofsulfuric acid is then introduced into the mixture. The mixture is heatedto reflux and water generated during the reaction is removed byazeotrope. The reaction is run overnight. The product is purified byprecipitation in methanol three times.

Example 13

[0057] This example discloses a polybutadiene base polymer with pendantstyrenic (electron donor) functionality,

[0058] One molar equivalent (based on anhydride function) ofpolybutadiene adducted with maleic anhydride (trade name: Ricon 131MA20, produced by Sartomer Company) is solvated in acetone, followed bythe dropwise addition of one molar equivalent of cinnamyl amine. Thereaction mixture is stirred for 6 hours. After acetone is removed byreduced pressure, the polymer is solvated in toluene and the product ispurified by precipitation in methanol three times.

Example 14

[0059] This example discloses a styrene/acrylic base polymer withpendant acrylate (electron acceptor) functionality.

[0060] where m=11 based on GPC and NMR analysis (one skilled in the artwill recognize that this value may vary slightly due to the polymericcharacter of the material).

[0061] In a 500 mL four-necked flask equipped with a mechanical stirrer,condenser, addition funnel and a N₂ inlet, was charged with 45.02 g of astyrene-acrylic polymer (Joncryl 587 from Johnson Polymer) in methylenechloride (100 mL). After the polymer was solvated under nitrogen at roomtemperature, the solution was cooled to 0° C. and 6.83 g oftriethylamine was added to the mixture. To this resulting mixture wasadded dropwise 6.11 g of acryloyl chloride. The mixture was allowed toreact for an additional 6 hours. After washing with aqueous solutionsseveral times until the aqueous phase is neutral, the resulting organiclayer was dried over Mg₂SO₄ and silica gel. After the solvents wereremoved under reduced pressure, a white solid was obtained.

Example 15

[0062] This example discloses a styrene/acrylic base polymer withpendant styrenic (electron donor) functionality,

[0063] where m=11 based on GPC and NMR analysis (one skilled in the artwill recognize that this value may vary slightly due to the polymericcharacter of the material).

[0064] In a 1 L four-necked flask equipped with a mechanical stirrer,condenser, addition funnel and a N₂ inlet, was charged with 126.7 g of astyrene acrylic polymer (Joncryl 587 from Johnson Polymer) in methylethyl ketone (620 mL). After the polymer was solvated at the refluxingtemperature of the solvent under nitrogen, 40.58 g of3-isopropenyl-α,α-dimethylbenzyl isocyanate (m-TMI) was added to themixture together with 0.12 g of dibutyltin dilaurate (catalyst). Theresulting mixture was heated for an additional twenty-four hours undernitrogen. After removal of the solvent under reduced pressure, a whitesolid was obtained in almost quantitative yield. According to GPCanalysis, the weight average molecular weight and the number averagemolecular weight of the modified styrene-acrylic polymer are 15,600g/mol and 8,400 g/mol, respectively. According to DSC analysis, theglass transition temperature of the modified styrene-acrylic polymer isapproximately 40° C.

Adhesive Film Examples Example 16

[0065] An adhesive film was prepared from a polymer system comprising anunsubstituted acrylic/rubber base polymer, an independent electronacceptor resin, an independent electron donor resin, and an epoxy resin,which components and parts by weight used are identified in Table 1. Thefilm formulation also contained a radical initiator, hardeners for theepoxy, a filler and adhesion promoters. TABLE 1 Component Chemical ClassParts or Function Source by wt. Base polymer SG-80DR 5 Acrylic rubberNagase ChemteX Corp. Electron acceptor Matrimid 5292A 3 BismaleimideCiba Specialty Chemicals Corporation Electron donor Adduct oftricyclodecane- 2.5 Structure I dimethanol/m-TMI Epoxy HP-7200H 3.5Dainippon Ink and Chemicals, Inc.

[0066] The electron donor had the following structure:

Structure I

[0067] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 17

[0068] An adhesive film was prepared from a polymer system comprising apoly(butadiene) base polymer substituted with pendant electron acceptorfunctionality, an independent electron acceptor resin, an independentelectron donor resin, and an epoxy resin, which components and parts byweight used are identified in Table 2. The film formulation alsocontained a radical initiator, hardeners for the epoxy, and adhesionpromoters. TABLE 2 Component Chemical Class Parts or Function Source bywt. Butadiene base polymer Polymer from Example 1. 2 substituted withpendant electron acceptor functionality Electron acceptor Matrimid 5292A1 Bismaleimide Ciba Specialty Chemicals Corporation Electron donorAdduct of tricyclodecane- 2.5 Structure I dimethanol/m-TMI EpoxyHP-7200H 3.5 Dainippon Ink and Chemicals, Inc.

[0069] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 18

[0070] An adhesive film was prepared from a polymer system comprising astyrene/acrylic base polymer substituted with pendant electron donorfunctionality, an independent electron acceptor resin, an independentelectron donor resin, and an acrylonitrile/butadiene rubber, whichcomponents and parts by weight used are identified in Table 3. The filmformulation also contained a radical initiator and adhesion promoters.TABLE 3 Component Chemical Class Parts or Function Source by wt.Sytrene/acrylic base polymer Polymer from Example 15 2 substituted withpendant electron donor functionality Electron acceptor Matrimid 5292A 5Bismaleimide Ciba Specialty Chemicals Corporation Electron donor Adductof 1.75 Structure I tricyclodecane- dimethanol/m-TMIAcrylonitrile/butadiene Zeon Chemicals 4 rubber

[0071] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 19

[0072] An adhesive film was prepared from a polymer system comprising astyrene/acrylic base polymer substituted with pendant electron donorfunctionality, an acrylonitrile/butadiene base polymer substituted withpendant electron donor functionality, an independent electron acceptorresin, an independent electron donor resin, which components and partsby weight used are identified in Table 4. The film formulation alsocontained a radical initiator, filler, and adhesion promoters. TABLE 4Component Chemical Class Parts or Function Source by wt. Sytrene/acrylicbase polymer Polymer from Example 15 2 substituted with pendant electrondonor functionality Acrylonitrile/butadiene base Polymer from Example 24 polymer substituted with pendant electron donor functionality Electronacceptor Matrimid 5292A 5 Bismaleimide Ciba Specialty ChemicalsCorporation Electron donor Adduct of 1.8 Structure I tricyclodecane-dimethanol/m-TMI

[0073] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 20

[0074] An adhesive film was prepared from a polymer system comprising aacrylonitrile/butadiene base polymer substituted with pendant electrondonor functionality, an independent electron acceptor resin, anindependent electron donor resin, and an epoxy, which components andparts by weight used are identified in Table 5. The film formulationalso contained a radical initiator, hardeners for the epoxy, filler, andadhesion promoters. TABLE 5 Component Chemical Class Parts or FunctionSource by wt. Acrylonitrile/butadiene base Polymer from Example 2 2.5polymer substituted with pendant electron donor functionality Electronacceptor Matrimid 5292A 3 Bismaleimide Ciba Specialty ChemicalsCorporation Electron donor Adduct of 2.5 Structure I tricyclodecane-dimethanol/m-TMI Epoxy HP-7200H 3.5 Dainippon Ink and Chemicals, Inc.

[0075] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 21

[0076] An adhesive film was prepared from a polymer system comprising aacrylonitrile/butadiene base polymer substituted with pendant electrondonor functionality, an independent electron acceptor resin, anindependent electron donor resin, and an epoxy, which components andparts by weight used are identified in Table 6. The film formulationalso contained a radical initiator, hardeners for the epoxy, filler, andadhesion promoters. TABLE 6 Component Chemical Class Parts or FunctionSource by wt. Acrylonitrile/butadiene base Polymer from Example 3 2.5polymer substituted with pendant electron donor functionality Electronacceptor Matrimid 5292A 3 Bismaleimide Ciba Specialty ChemicalsCorporation Electron donor Adduct of 2.5 Structure I tricyclodecane-dimethanol/m-TMI Epoxy HP-7200H 3.5 Dainippon Ink and Chemicals, Inc.

[0077] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Example 22

[0078] An adhesive film was prepared from a polymer system comprising anacrylonitrile/butadiene base polymer substituted with pendant electronacceptor functionality, a styrene/acrylic base polymer substituted withpendant electron donor functionality, an independent electron acceptorresin, an independent electron donor resin, which components and partsby weight used are identified in Table 7. The film formulation alsocontained a radical initiator. TABLE 7 Component Chemical Class Parts orFunction Source by wt. Acrylonitrile/butadiene base Polymer from Example1 2.5 polymer substituted with pendant electron donor functionalityStyrene/acrylic base polymer Polymer from Example 3 substituted withpendant 15 electron donor functionality Electron acceptor Matrimid 5292A5 Bismaleimide Ciba Specialty Chemicals Corporation Electron donorAdduct of 1.8 Structure I tricyclodecane- dimethanol/m-TMI

[0079] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Comparative Adhesive Film Example Example 23

[0080] This example discloses an adhesive film prepared with a polymericsystem containing an acrylonitrile/butadiene base polymer, and epoxyresin, and no electron donor nor electron acceptor functionality. Theformulation also contained a phenol novolak resin and curing agents. Theformulation components and parts by weight are disclosed in Table 8.TABLE 8 Component Chemical Class Parts or Function Source by wt.Acrylonitrile/butadiene Nipol 1072 2.7 rubber Zeon Chemicals EpoxyHP-7200H 3.5 Dainippon Ink and Chemicals, Inc. Phenol Novolak resinHRJ-1166 1 Schenectady International Inc.

[0081] The film formulation was prepared by mixing the components inmethyl ethyl ketone with stirring, followed by vacuum degassing. Thevarnish obtained was coated to a thickness of 2 mil onto a 5 mil thicksilicone-treated release-liner and then dried by heating at 100° C. for10 minutes to form a partially cured adhesive film with a thickness of 1mil.

Performance Examples Example 24

[0082] A sample of each film produced in Examples 16-22 and ComparativeExample 23 was used to bond a 100 by 100 square mil silicon die to a PIflex substrate at 120° C. in 5 seconds and cured at 180° C. for oneminute. The die shear strength of these bare packages was measured at180° C. on a Dage Series 4000 Bondtester.

[0083] The results are disclosed in Table 9 and demonstrate that theinventive films have superior adhesive strength. TABLE 9 DIE SHEARSTRENGTH in Kg Force @ 180° C. Cure condition 180° C./1 min Die shearstrength measure 180° C. temperature Example 16 1.86 Example 17 0.90Example 18 2.22 Example 19 1.93 Example 20 2.78 Example 21 2.80 Example22 3.00 Comparative Example 23 0.26

What is claimed:
 1. A film adhesive prepared from materials comprising(i) a polymer containing no electron donor or acceptor functionalityhaving a molecular weight in the range of 2,000 to 1,000,000, (ii) anindependent electron donor compound and (iii) an independent electronacceptor compound.
 2. The film adhesive according to claim 1 in whichthe polymer (i) is prepared from acrylic, vinyl, or conjugated dienemonomers.
 3. The film adhesive according to claim 2 in which the polymer(i) is an acrylic polymer, a styrene-acrylic copolymer, or aacrylonitrile-butadiene copolymer.
 4. The film adhesive according toclaim 1 in which the independent electron donor compound is selectedfrom the group consisting of vinyl ethers, vinyl silanes, and compoundscontaining a carbon to carbon double bond attached to an aromatic ringand conjugated with the unsaturation in the ring.
 5. The film adhesiveaccording to claim 4 in which the vinyl ethers are selected from thegroup consisting of bis[4-(vinyloxy)butyl]terephthalate,bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)biscarbamate,bis[4-(vinyloxy) butyl]1,6-hexanediylbiscarbamate, 4-(vinyloxy)butylstearate, and bis[4-(vinyloxy)butyl](methylenedi-4,1-phenylene)biscarbamate.
 6. The film adhesiveaccording to claim 4 in which the compounds containing a carbon tocarbon double bond attached to an aromatic ring and conjugated with theunsaturation in the ring are selected from the group consisting of:


7. The film adhesive according to claim 1 in which the independentelectron acceptor compound is selected from the group consisting offumarates, maleates, acrylates, and maleimides.
 8. The film adhesiveaccording to claim 7 in which the independent electron acceptor compoundis a bismaleimide selected from the group consisting ofN,N′-ethylene-bis-maleimide, N,N′-butylene-bis-maleimide,N,N′-phenylene-bis-maleimide, N,N′-hexamethylene-bis-maleimide,N,N′-4,4′-diphenyl methane-bis-maleimide, N,N′-4,4′-diphenylether-bis-maleimide, N,N′-4,4′-diphenyl sulfone-bis-maleimide,N,N′-4,4′-dicyclohexyl methane-bis-maleimide,N,N′-xylylene-bis-maleimide, and N,N′-diphenylcyclohexane-bis-maleimide.
 9. A film adhesive prepared from (i) apolymer substituted with pendant electron acceptor functionality havinga molecular weight in the range of 2,000 to 1,000,000, (ii) anindependent electron donor compound, and optionally (iii) an independentelectron acceptor compound.
 10. The film adhesive according to claim 9in which the polymer (i) is prepared from acrylic, vinyl, or conjugateddiene monomers and has pendant electron acceptor functionality.
 11. Thefilm adhesive according to claim 10 in which the polymer (i) is anacrylic, styrene-acrylic copolymer, or a acrylonitrile-butadienecopolymer and has pendant electron acceptor functionality.
 12. The filmadhesive according to claim 9 in which the independent electron donorcompound is selected from the group consisting of vinyl ethers, vinylsilanes, and compounds containing a carbon to carbon double bondattached to an aromatic ring and conjugated with the unsaturation in thering.
 13. The film adhesive according to claim 12 in which the vinylethers are selected from the group consisting ofbis[4-(vinyloxy)butyl]terephthalate,bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)biscarbamate,bis[4-(vinyloxy) butyl]1,6-hexanediylbiscarbamate, 4-(vinyloxy)butylstearate, and bis[4-(vinyloxy)butyl](methylenedi-4,1-phenylene)biscarbamate.
 14. The film adhesiveaccording to claim 12 in which the compounds containing a carbon tocarbon double bond attached to an aromatic ring and conjugated with theunsaturation in the ring are selected from the group


15. The film adhesive according to claim 9 in which the independentelectron acceptor compound is selected from the group consisting offumarates, maleates, acrylates, and maleimides.
 16. The film adhesiveaccording to claim 15 in which the independent electron acceptorcompound is a bismaleimide selected from the group consisting ofN,N′-ethylene-bis-maleimide, N,N′-butylene-bis-maleimide,N,N′-phenylene-bis-maleimide, N,N′-hexamethylene-bis-maleimide,N,N′-4,4′-diphenyl methane-bis-maleimide, N,N′-4,4′-diphenylether-bis-maleimide, N,N′-4,4′-diphenyl sulfone-bis-maleimide,N,N′-4,4′-dicyclohexyl methane-bis-maleimide,N,N′-xylylene-bis-maleimide, and N,N′-diphenylcyclohexane-bis-maleimide.
 17. A film adhesive prepared from (i) apolymer having pendant electron donor functionality having a molecularweight in the range of 2,000 to 1,000,000, (ii) an independent electronacceptor compound and optionally (iii) an independent electron donorcompound;
 18. The film adhesive according to claim 17 in which thepolymer (i) is prepared from acrylic, vinyl, or conjugated dienemonomers and has pendant electron donor functionality.
 19. The filmadhesive according to claim 18 in which the polymer (i) is an acrylic, astyrene-acrylic copolymer, or a acrylonitrile-butadiene copolymer andhas pendant electron donor functionality.
 20. The film adhesiveaccording to claim 17 in which the independent electron acceptorcompound is selected from the group consisting of fumarates, maleates,acrylates, and maleimides.
 21. The film adhesive according to claim 20in which the independent electron acceptor compound is a bismaleimideselected from the group consisting of N,N′-ethylene-bis-maleimide,N,N′-butylene-bis-maleimide, N,N′-phenylene-bis-maleimide,N,N′-hexamethylene-bis-maleimide, N,N′-4,4′-diphenylmethane-bis-maleimide, N,N′-4,4′-diphenyl ether-bis-maleimide,N,N′-4,4′-diphenyl sulfone-bis-maleimide, N,N′-4,4′-dicyclohexylmethane-bis-maleimide, N,N′-xylylene-bis-maleimide, and N,N′-diphenylcyclohexane-bis-maleimide.
 22. The film adhesive according to claim 17in which the independent electron donor compound is selected from thegroup consisting of vinyl ethers, vinyl silanes, and compoundscontaining a carbon to carbon double bond attached to an aromatic ringand conjugated with the unsaturation in the ring.
 23. The film adhesiveaccording to claim 22 in which the vinyl ethers are selected from thegroup consisting of bis[4-(vinyloxy)butyl]terephthalate,bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)biscarbamate,bis[4-(vinyloxy) butyl]1,6-hexanediylbiscarbamate, 4-(vinyloxy)butylstearate, and bis[4-(vinyloxy)butyl](methylenedi-4,1-phenylene)biscarbamate.
 24. The film adhesiveaccording to claim 22 in which the compounds containing a carbon tocarbon double bond attached to an aromatic ring and conjugated with theunsaturation in the ring are selected from the group consisting of:


25. A film adhesive prepared from (i) a polymer having pendant electrondonor and electron acceptor functionality and having a molecular weightin the range of 2,000 to 1,000,000, or a combination of a polymer havingpendant electron donor functionality and having a molecular weight inthe range of 2,000 to 1,000,000, and a polymer having pendant electronacceptor functionality and having a molecular weight in the range of2,000 to 1,000,000; optionally (ii) an independent electron donorcompound; and optionally (iii) an independent electron acceptorcompound.
 26. The film adhesive according to claim 25 in which thepolymer (i) is prepared from acrylic, vinyl, or conjugated dienemonomers and has pendant electron donor functionality and pendantelectron acceptor functionality and the polymers in the combination of apolymer having pendant electron donor functionality and a polymer havingpendant electron acceptor functionality polymers (i) are prepared fromacrylic, vinyl, or conjugated diene monomers with, respectively, pendantelectron donor functionality and pendant electron acceptorfunctionality.
 27. The film adhesive according to claim 26 in which thepolymer (i) is an acrylic, a styrene-acrylic copolymer, or aacrylonitrile-butadiene copolymer and has pendant electron donorfunctionality and pendant electron acceptor functionality, and thepolymers in the combination of a polymer having pendant electron donorfunctionality and a polymer having pendant electron acceptorfunctionality polymers (i) is an acrylic, a styrene-acrylic copolymer,or a acrylonitrile-butadiene copolymer with, respectively, pendantelectron donor functionality and pendant electron acceptorfunctionality. 28 The film adhesive according to claim 25 in which theindependent electron donor compound is selected from the groupconsisting of vinyl ethers, vinyl silanes, and compounds containing acarbon to carbon double bond attached to an aromatic ring and conjugatedwith the unsaturation in the ring.
 29. The film adhesive according toclaim 28 in which the vinyl ethers are selected from the groupconsisting of bis[4-(vinyloxy)butyl]terephthalate,bis[4-(vinyloxy)butyl](4-methyl-1,3-phenylene)biscarbamate,bis[4-(vinyloxy) butyl]1,6-hexanediylbiscarbamate, 4-(vinyloxy)butylstearate, and bis[4-(vinyloxy)butyl](methylenedi-4,1-phenylene)biscarbamate.
 30. The film adhesiveaccording to claim 28 in which the compounds containing a carbon tocarbon double bond attached to an aromatic ring and conjugated with theunsaturation in the ring are selected from the group consisting of:


31. The film adhesive according to claim 25 in which the independentelectron acceptor compound is selected from the group consisting offumarates, maleates, acrylates, and maleimides.
 32. The film adhesiveaccording to claim 31 in which the independent electron acceptorcompound is a bismaleimide selected from the group consisting ofN,N′-ethylene-bis-maleimide, N,N′-butylene-bis-maleimide,N,N′-phenylene-bis-maleimide, N,N′-hexamethylene-bis-maleimide,N,N′-4,4′-diphenyl methane-bis-maleimide, N,N′-4,4′-diphenylether-bis-maleimide, N,N′-4,4′-diphenyl sulfone-bis-maleimide,N,N′-4,4′-dicyclohexyl methane-bis-maleimide,N,N′-xylylene-bis-maleimide, and N,N′-diphenylcyclohexane-bis-maleimide.